FIGS. 22-24 illustrate the structure of a conventional grand piano, and FIG. 21 illustrates a process of assembling the same. Conventionally, a grand piano is generally assembled in accordance with the following procedure:
A. First, a backpost 1, an inner rim 2, a back beam 3, and so on are "tenoned together" to assemble a backpost assembly 4.
B. After the top surface of the inner rim 2 is formed with a curved plane and grooves for accommodating sound ribs therein, a sound board 8 having sound ribs 6 and bridges 7 (a long bridge 7a and a short bridge 7b) previously mounted thereon is adhered to the top surface of the inner rim 2. Subsequently, the outer periphery of the adhered sound board 8 is ground for reshaping such that the outer periphery of the sound board 8 matches the outer periphery of the inner rim 2.
C. A pin block 9 and a plate 12 are once placed on the sound board 8 for defining the height of the bridges. Specifically, a bridge height line is drawn on side surfaces of the respective bridges using a previously provided jig, and top surfaces of the bridges are ground to the bridge height line to define a predetermined bridge height.
D. After defining the bridge height, the plate 12 and the pin block 9 are removed, and each of the bridges 7 is cut to form recesses in the top surface thereof for carrying strings thereon, and the lengths of vibrating portions of the strings are defined. In parallel, the removed plate 12 is painted, and hitch pins 14 and agraffe 15 are mounted on the plate 12.
E. A previously formed outer rim 10 is adhered to the outer periphery of the inner rim 2 of the backpost assembly 4. The outer rim 10 is made, for example, of a laminated plate having a total of 15 layers of lauan plywood and decorative single plates of makore adhered to the top and rear surfaces of the lauan plywood laminate. These lauan plywood and decorative single pates are laminated and inserted between an outer mold and an inner mold of a pressing machine, wherein they are pressurized, adhered, and formed into a shape matching the configuration of the inner rim 2.
F. Next, the frontage dimension of the outer rim 10, i.e., the dimension between the inner surfaces of the left and right front ends of the inner rim 2 is adjusted. Specifically, if the frontage dimension, with the outer rim 10 attached thereto, is smaller than a predetermined dimension, the inner surfaces of the inner rims 2 are cut to adjust the frontage dimension.
G. The inner rim 2 and the outer rim 10 are formed with arms at left and right front portions thereof. Specifically, the left and right front portions of the inner rim 2 and the outer rim 10 are respectively cut so as to match predetermined shapes of the respective arms.
H. Next, a decorative single plate (not shown) is glued on each cut surface, and the surfaces of the outer rim 10 and the inner rim 2 including the decorative single plates are spray-painted by a spray gun (base painting).
I. A previously formed and painted keybed 11 is fixed on the lower surface of the outer rim 10 between the left and right ends of the outer rim 10.
J. A pin block 9 is fixed between the left and right front ends of the inner rim 2 of the backpost assembly 4. The plate 12 is also fixed to the backpost assembly 4 in a state in which the plate 12 is carried on the sound board 8 and the pin block 9. Subsequently, after tuning pins 13 are embedded into the pin block 9 through the plate 12, strings S are stretched between the tuning pins 13 and the hitch pins 14 through the bridges 7.
K. Next, a vertical bosom space (the vertical distance from the top surface of the keybed 11 to a string securing points of the strings S) is measured, and the top surface of the keybed 11 is cut for adjustment to define a predetermined dimension of the vertical bosom space. The measurement and adjustment of the vertical bosom space are made using a large keybed cutting machine having a sensor.
L. Large leg blocks 17 and small leg blocks 18 are mounted in order, and then legs 19 and pedals 20 are mounted.
M. Next, a damper unit 21 is mounted to a back beam 3 of the backpost assembly 4, and a keyframe 25 having a keyboard 22, an action 23, and a hammer head 24 previously set thereon is incorporated into the keybed 11, followed by adjustments which are made therefor.
N. Finally, a keyslip 26, cheekblocks 27, a topboard rear 28, a topboard front 29, and so on, i.e., casing parts 30 other than the outer rim 10 are all mounted in place (mounting of parts after the outer rim is formed). Then, the assembly undergoes inspections including finished sound tuning, check for external appearance, and so on. Thus, the assembly of the piano is completed.
Conventionally, the outer rim of a grand piano is integrally formed so as to define the configuration of the grand piano. Such an outer rim is made of a laminated plate composed of approximately 15 layers, for example, including a plurality of single plates of lauan and decorative single plates of birch or makore placed on front and rear surfaces, approximately having a total length of 4-6 meters, a width of 30 centimeters, and a thickness of 4 millimeters. Such an outer rim is generally manufactured in the following steps (A1)-(A3).
(A1) First, for each of single plates, an expert manually curves the plate while it is exposed to a vapor (a single plate forming step).
(A2) Next, the single plates are inserted into an outer mold and an inner mold of a large pressing machine, pressed and adhered to adjacent ones. In this way, the plates are formed into a shape matching the configuration of an inner rim having the configuration of a grand piano (a pressing step).
(A3) Next, after mounted to the inner rim, the laminated plates are repeatedly spray-painted by a spray gun to complete an outer rim (a painting step).
FIG. 25 illustrates a conventional arm for a piano and a fabricating method thereof. An arm 100 is fabricated by adhering a continuous single outer rim 105 along the outer periphery of an inner rim 107 having the configuration of a grand piano, and performing the following processing on front end portions of the inner rim 107 and the outer rim 105. The inner rim 107 is made of wood, for example, by stacking thick solid plates of elm, matoa, or the like in a block-like form. The outer rim 105 is made of plywood composed of a laminate of a plurality of single plates of lauan or the like and decorative single plates of birch, makore, or the like. The plywood has been previously curved into a predetermined shape.
(B1) First, as illustrated in FIG. 25(a), a music shelf support rail 101 is adhered to an inner surface of a front end portion of the outer rim 105 such that it comes into contact with the top surface of the inner rim 107 and its top surface is coplanar with that of the outer rim 105. The music shelf support rail 101 is made of plywood similar to that of the outer rim 105.
(B2) Next, as illustrated in FIG. 25(b), a cutting machine is used to cut the music shelf support rail 101 together with the outer rim 105 and the inner rim 107 into a shape conformal to the design of the arm 100, and a decorative single plate 108 is adhered to the cut surface.
(B3) Then, the surface including the decorative single plate 108 is painted to complete the arm 108 as illustrated in FIG. 25(c).
FIG. 26 is a cross-sectional view illustrating a keyslip mounting portion of a keybed in a conventional keyboard musical instrument, for example, a grand piano. As illustrated in FIG. 26, conventionally, at a top surface end of a keybed 11 on which a keyboard is positioned through a keyframe (either not shown), a keyslip 112 is mounted for preventing a player from viewing the bottom surface of the keyboard to provide a fine appearance near the keyboard as well as for abutting to a fallboard (not shown) to cover the keyboard. The keyslip 112 is formed with a plurality of dowels 112a on a longitudinal lower surface and with a cheekblock attachment 12b on a back surface for engagement with a cheekblock 27. Then, as illustrated in FIG. 26, the dowels 112a are inserted into associated dowel inserting holes 13a formed in end portions of the top surface of the keybed 11, while the cheekblock attachment 12b is engaged with a keyslip stopper 27a formed in an end portion of the cheekblock 27. In this way, the keyslip 112 is mounted to an end portion of the top surface of the keybed 11.
FIG. 27 is a cross-sectional view illustrating a keyslip mounting portion on a keybed in another conventional keyboard musical instrument, for example, an upright piano. As illustrated in this FIG. 27, a keyslip block 122a is attached on a back surface of a keyslip 122, while a keyslip engaging portion 123a is formed in an end portion of a top surface of the keybed 11. Then, the back surface of the keyslip 122 abuts to a front surface 123b of the keybed 11, and the keyslip block 122a engages with the engaging portion 123a of the keybed 11 and is fixed by a screw 121, whereby the keyslip 122 is mounted to the front surface 123b of the keybed 11.
On the top surfaces of the keybed 11 and the keyslip block 122a, a keyframe 25 is positioned, and a plurality of keys 22 comprising white keys and black keys are positioned above the keyframe 25. Incidentally, a front pin 126 is attached to an end portion of a top surface of the keyframe 25 in order to prevent the keys 22 from vibrating in the width direction.
As mentioned above, in the conventional assembling method, the backpost assembly 4 is positioned as a base, and parts are mounted thereto in order, and predetermined processing and painting are performed for them to assemble a grand piano. In other words, since mounting, processing and so on of parts are directed to the heavy and large backpost assembly 4, except for a portion of separately prepared parts, from the start to the end of assembly, this causes difficulties in handling during the assembly, an increase in scale of machines and facilities for attachment, and so on, thereby incurring a drawback that an assembling cost is increased.
For example, since the outer rim 10 is formed as a single continuous curved plate conformal to the configuration of the inner rim 2 of the backpost assembly 4, a pressing machine therefor is necessarily large. For the same reason, machine tools for forming a curved surface of the inner rim 2, making arms on the outer rim 10 and so on, painting facilities for performing base painting and so on, and other machines are obliged to be also large. Further, since the outer rim 10 is formed of a single curved plate, painting therefor must be performed using a paint having a relatively small flow-out by repeating a spray painting step and a drying step a large number of times so as to prevent the paint from dropping down on the outer rim, thus requiring an extremely long time for the painting step.
Also, in the conventional assembling method, since the backpost assembly 4 is positioned as a base such that most of steps such as mounting and processing of parts are advanced in order, in a so-called serial assembling line, the assembly cannot proceed to a next step unless the previous step is completed. For example, since strings are stretched after the plate 12 is mounted to the backpost assembly 4 and the tuning pins 13 are embedded, the time-consuming step of embedding the tuning pins 13 causes stagnation on the assembling line, resulting in a degraded manufacturing efficiency.
Furthermore, in the conventional assembling method, since the plate 12 is carried on the pin block 9, the thickness of the pin block 9 may directly affect the height at which the strings S are positioned, and hence the bridge height. For this reason, the aforementioned adjustment of the bridge height is required. If the thickness of the pin block 9 is less accurate, the adjustment of the bridge height will require significant labor and time.
In addition, since the plate 12 is mounted and the strings are stretched after the keybed 11 is fixed to the outer rim 10, the tensile forces of the strings S may cause deformations such as bow and twist to the backpost assembly 4 and the outer rim 10 which are made of wood materials. Due to the influence of such deformations, positional relationships between parts, for example, the vertical bosom space, are more susceptible to large shift. On the other hand, since the keybed 11 has already been fixed to the outer rim 10, adjustment of the vertical bosom space will require, for example, a large keybed cutting machine having a sensor for cutting the keybed 10. This also causes an increase in the assembling cost.
The above-mentioned conventional outer rim and manufacturing method thereof have, first of all, a drawback that objects to be processed are large and difficult to handle commonly over all manufacturing steps because of the integrally formed outer rim. Also, since each manufacturing step requires a wider space, a factory or the like must have a wide area, resulting in an increase in facility cost, operation cost and so on of the factory. Further, dedicated machines such as a large pressing machines required for use in the aforementioned (A2) pressing step additionally increases the facility cost.
In addition to the foregoing, in the aforementioned (A1) single plate forming step, since an expert must manually curve, with patient, the large single plate which is difficult to handle, a processing period becomes longer, and accordingly a processing cost is also increased. Further, as mentioned above, not only a large number of materials such as a large dimension single plate are required, but they cannot be used unless they are satisfactorily processed. Frequently occurring processing errors would result in a lower material yield, which constitutes a factor of increasing a processing cost and a material cost.
In the aforementioned (A3) painting step, the conventional method of assembling a grand piano has a problem of a longer painting period, as previously mentioned in relation to the outer rim.
Also in the aforementioned conventional arm and manufacturing method thereof, since the arm 100 is processed for the large and heavy outer rim 105 and inner rim 107, after the outer rim 105 has been adhered to the inner rim 107, i.e., after they have been shaped into the configuration of a grand piano, the facility cost is increased for the reasons mentioned in connection with the aforementioned conventional method of assembling a grand piano. Also, in the painting step, a time required for the painting becomes longer for the reason mentioned above, so that the entire manufacturing period is prolonged.
The keyslip mounting portion of the keybed in the aforementioned keyboard musical instrument has problems as follows when a keyboard, an action and so on are adjusted. Specifically, for adjusting the keyboard, the action and so on in the case of a grand piano, they are generally pulled out in front together with a keyframe, so that the keyslip must be removed from the keybed. However, since the keyslip mounting portion has a structure as illustrated in FIG. 26, the cheekblock 27 must be removed from the top surface of the keybed 11 before the keyslip 112 is removed from the keybed 11. Also, as illustrated in FIG. 26, when the keyslip 112 is mounted to an end portion of the top surface of the keybed 11, the front surface 113b of the keybed 11 is also exposed, which is not favorable in an esthetics point of view. Thus, for such a case, a decorative single plate (not shown) must be attached to the front surface 113b of the keybed 11 and painted.
For an upright piano, in turn, since the keyslip mounting portion has a structure as illustrated in FIG. 27, it is necessary, for removing the keyslip 122, to first remove the keyframe 25 and the keyboard 22 positioned on the top surface of the keybed 11 and the keyslip block 122a, and to next remove the screws 121. For this reason, the removal of the keyslip 112 is complicated.